Tool Unit

ABSTRACT

A tool unit for a handheld power tool having an oscillating output unit, having a fastening means ( 3 ) for attachment to the output unit, and having a working edge ( 4 ) that transitions into a lateral boundary line ( 7, 8, 12, 13, 16, 17 ). 
     The working edge ( 4 ) is arc-shaped.

PRIOR ART

The invention is based on a tool unit for a handheld power toolaccording to the preamble to claim 1.

In a handheld power tool with an oscillating output unit, for exampleembodied in the form of an output shaft, the shaft oscillates back andforth between two angular positions at a high frequency. Thisoscillation is transmitted to the tool unit attached to the outputshaft. Depending on the tool unit, a handheld power tool of this kindcan be used in a very wide variety of ways. It is thus possible to usethe handheld power tool for sharpening, sawing, and grinding workpieces, for cutting work pieces, or for removing joining material, floorcoverings, or tiles.

EP 0 881 023 A2 has disclosed a cutting and grinding tool for a handheldpower tool equipped with an output shaft that executes an oscillatingpivoting motion. The tool unit disclosed therein has a working edgecomposed of two or more cutting and/or grinding edges situated at anangle in relation to each other.

ADVANTAGES OF THE INVENTION

The invention is based on a tool unit for a handheld power tool havingan oscillating output unit, having a fastening means for attachment tothe output unit, and having a working edge that transitions into alateral boundary line.

According to the present invention, the working edge is arc-shaped. Auniform cut in a work piece can be produced with a uniform stress on theworking edge. The arc-shaped working edge is used to machine the workpiece. The arc shape not only permits the tool unit to advancelaterally, perpendicular to the cutting direction but also, by simplychanging the attitude of the handheld power tool, permits the tool unitto be used in almost any way to machine the work piece, in particularfor grinding, cutting, sawing, clearing, or disk cutting. The tool unitdoes not need to be changed to accomplish this.

The attaching means serves to transmit a working motion. The workingedge can extend at an angle in relation to the lateral boundary line.The attaching means can be embodied in almost any way. Thus, forexample, a rod-shaped design known from drill attachments isconceivable, in which the rod is attached to the drive shaft by means ofa rotary chuck, a screw chuck, or a quick-release chuck. It is alsopossible, however, to use a burr connection, a clamped connection, or ascrew connection. In particular, it is also possible to provide anopening in the tool unit, which accommodates the output shaft and servesto connect the tool unit to this shaft.

Essentially, the arc of the working edge can be embodied in almost anyform; in particular, it is conceivable to embody it in a parabolic,hyperbolic, or elliptical shape. The arc-shaped working edge isadvantageously constituted by the circumference of a circle around whosecenter point the fastening means is situated, in particular centered inthe circle. With this design, when the output shaft of the handheldpower tool oscillates, no vibration is imparted to the tool unit in theadvancing direction or in the direction perpendicular to the workingedge. In addition, this permits the tool unit to be used in acomparatively stable, multifunctional fashion. The circular designpermits the tool unit, through simple rotation of the handheld powertool, to be used to machine a work piece, e.g. for grinding, cutting,sawing, clearing, or disk cutting.

In an advantageous embodiment of the present invention, the working edgeis situated at an angle of less than or equal to 95° in relation to thelateral boundary line on at least one side. With a tool unit designed inthis fashion, in a vertical guide, as the tool unit advances along thelateral boundary line, the deepest point of the advancing motion issituated in the corner between the arc-shaped working edge and thelateral boundary line. Between the bottom of the guide and the lateralcut edge, there is no longer any residual cross-section of the workpiece since the cutting action is executed here, too, due to theselected geometry of the tool unit. It is not necessary to penetratedeeper than the thickness of the work piece in order to cut through partof a work piece.

If the angle between the working edge and the lateral boundary line is90°, then the above-described advancing of the tool unit produces aright angle between the bottom of the cut and the lateral cut edge. Ifthe angle is less than 90°, then the tool unit can even produce an acuteangle between the cut bottom and the cut edge. An angle of at most 5°greater than 90° is still tolerable due to the oscillation of theworking edge. With an angle of greater than 95°, the above-describedadvantage is no longer achieved.

The tool unit itself—apart from the angle between the working edge andthe lateral boundary line—can have virtually any outer form depending onthe area in which it is to be used and on the respective handheld powertool. In particular, the tool unit can also be embodied as goosenecked.

In another advantageous embodiment, the arc-shaped working edge isconstituted by the circumference section of a circle sector; each of thetwo ends of the working edge is situated at an angle in relation to arespective lateral boundary line extending in the radial direction. Theangle between the two lateral boundary lines that define the circlesegment should advantageously lie between 30° and 270°. If the angle issmaller, then the tool unit is susceptible to change with regard to therequired length of the working edge in relation to the length of theboundary line required here. With a larger angle, the cut produced bythe tool unit can only be of limited depth.

For the mechanical stability of the tool unit, it is useful for theradially extending boundary lines to be connected to each other by meansa connecting contour before they reach the center point. This connectingcontour can be embodied in almost any way, in particular with arc-shapedtransitions. Embodying the tool unit with a connecting contour alsoleaves more space available for the attachment of the fastening means.

The arc-shaped working edge is advantageously constituted by thecircumference section of a circle segment; each of the two ends of theworking edge is situated at an angle in relation to a respectiveboundary line, each of which is essentially constituted by the straightsection of the circle segment. With a large radius of the circlesegment, this design permits particularly deep cuts to be made. Thecircle segment can be laterally elongated in a corresponding fashion inorder to attach the fastening means.

The working edge is the one that is used to machine the work piece. Theworking edge is responsible for advancing the tool unit and can beembodied in numerous ways. Depending on its intended use, it can beembodied as a sharp cutting edge or can be provided with a rough orabrasive covering such as diamond or corundum. The edge itself can alsobe embodied as flat or broad in order to act on a work piece in a forexample grinding or machining fashion. For a perpendicular cut into awork piece, it is particularly advantageous if the working edge isprovided with saw teeth.

DRAWINGS

Additional advantages ensue from the following description of thedrawings. The drawings show exemplary embodiments of the presentinvention. The drawings, the specification, and the claims containnumerous defining characteristics in combination. Those skilled in theart will also consider these defining characteristics individually andunite them in other meaningful combinations.

FIG. 1 shows a tool unit with a working edge in the form of anellipsoidal arc,

FIG. 2 shows a tool unit in the form of a circle segment, with aconnecting contour,

FIG. 3 shows another tool unit in the form of a circle segment.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows a tool unit for a handheld power tool with an oscillatingoutput shaft that makes it possible to produce a perpendicular cut in awork piece. The tool unit has an opening or bore that accommodates theoutput shaft of the handheld power tool. The oscillating, rotary motionof the output shaft moves the tool unit back and forth between twoangular positions, as is schematically depicted by the arrows. In thismanner, a work piece is machined by means of a working edge 4 equippedwith saw teeth. The oscillation range measures 4°. The working edge 4 isembodied in the form of an ellipsoidal arc 5, each of whose ends issituated at an angle 10 of 90° in relation to the lateral boundary lines7 and 8. In this way, as the tool unit produces a cut, at each of thelateral defining lines 7 and 8, a clean corner is cut from the workpiece, with a 90° angle between the bottom of the cut and the edge ofthe cut.

The tool unit according to FIG. 2 is embodied in the form of a circlesector 11, which has a fastening means 3 in the form of a bore at thecenter point of the circle to accommodate the output shaft of a handheldpower tool. The circle sector 11 is essentially comprised of the workingedge 4, which has the form of a circular arc 5′, and two lateralboundary lines 12 and 13 extending in the radial direction. The boundarylines 12 and 13 are connected to each other via a connecting contour 14that has arc-shaped connections.

FIG. 2 also shows a machined work piece 20. The cut 21 that the toolunit produces in the work piece 20 is clearly visible. The cut 21 has acut bottom 22 and a cut edge 23. The right angle between the workingedge 4 and the lateral boundary line 12 of the tool unit produces alikewise right angle between the cut bottom 22 and the cut edge 23. Noresidual material of the work piece 20 is left in the corner.

The working edge 4 of the tool unit according to FIG. 3 is part of thecircumference of a circle segment 24 that is comprised of the workingedge 4 and lateral boundary lines 16 and 17 lying on a straight line. Anextension contains a fastening means once again embodied as a boresituated at the center point. It is clear that the angle of less than90° between the working edge 4 and the lateral boundary line 16 makes itpossible to produce a cut 21 in the work piece 20 in which there is anacute angle between the cut bottom 22 and the cut edge 23.

REFERENCE NUMERALS

-   3 fastening means-   4 working edge-   5 ellipsoidal arc-   5′ circular arc-   7, 8 boundary line-   10 angle-   11 circle sector-   12, 13 boundary line-   14 connecting contour-   16, 17 boundary line-   20 work piece-   21 cut-   22 cut bottom-   23 cut edge-   24 circle segment

1. A tool unit for a handheld power tool having an oscillating outputunit, having a fastening means (3) for attachment to the output unit,and having a working edge (4) that transitions into a lateral boundaryline (7, 8, 12, 13, 16, 17), wherein the working edge (4) is arc-shaped.2. The tool unit as recited in claim 1, wherein the arc-shaped workingedge (4) is constituted by the circumference of a circle around whosecenter point the fastening means (3) is situated.
 3. The tool unit asrecited in claim 1, wherein at least one end of the working edge (4) issituated at an angle (10) of less than or equal to 95° in relation tothe lateral boundary line (7, 8, 12, 13, 16, 17) on at least one side.4. The tool unit as recited in claim 1, wherein the working edge (4) isconstituted by the circumference section of a circle sector (11) andeach of the two ends of the working edge (4) is situated at an angle inrelation to a respective lateral boundary line (12, 13) extending in theradial direction.
 5. The tool unit as recited in claim 4, wherein thecircle sector (11) extends over an angular range of between 30° and270°.
 6. The tool unit as recited in claim 4, wherein the radiallyextending boundary lines (12, 13) are connected to each other by means aconnecting contour (14) before they reach the center point.
 7. The toolunit as recited in claim 1, wherein the working edge (4) is constitutedby the circumference of a circle segment (24) and each of the two endsof the working edge (4) is situated at an angle in relation to arespective lateral boundary line (16, 17), each of which is essentiallyconstituted by the straight section of the circle segment (24).
 8. Thetool unit as recited in claim 1, wherein the working edge (4) isprovided with saw teeth.